Project Summary/Abstract Chronic pain affects more than 100 million people in the United States and produces annual costs up to $635 billion. While pain affects all segments of the population, the burden of chronic pain and associated disability disproportionately affects non-Hispanic Blacks (?Blacks?) compared to non-Hispanic Whites (?Whites?) as well as individuals with low socioeconomic status (SES) compared to those with high SES. Blacks often experience more frequent, severe and disabling chronic pain compared to Whites. Further, SES factors, such as lower levels of education, low income, and unemployment are associated with higher rates of chronic and disabling pain. Despite growing documentation of racial differences in chronic pain outcomes, relatively little research has focused on differences in the experience of chronic low back pain (cLBP) between Blacks and Whites in a socioeconomic context. This is concerning because cLBP is one of the most prevalent and severely disabling painful conditions, yet it remains unclear whether specific disadvantaged subgroups of society such as Blacks with low SES may be at heightened risk for poor cLBP outcomes. The proposed hypotheses are based on the theory of fundamental causes as a socioeconomic framework for explaining why cLBP severity and disability, as well as the factors predicting these outcomes, may differ as a function of racial background. Guided by the theory of fundamental causes, the overall aim of this study is to characterize racial and SES differences in cLBP severity and disability. Further, we aim to examine important biopsychosocial predictors of racial and SES differences in cLBP outcomes. To explore this overall aim, we will first characterize racial and SES differences in cLBP clinical symptoms, perceived disability, and functional performance. Next, we will invoke endogenous pain inhibitory and facilitatory processes using quantitative sensory tests of conditioned pain modulation and temporal summation, respectively. Biologically-driven factors including sleep, vitamin D, oxytocin, and C-reactive protein, in addition to psychosocial factors including depressive symptoms, racial discrimination, perceived injustice, access to social support, and psychological resilience will then be assessed. We will determine whether endogenous pain modulatory processes, as well as important biopsychosocial factors differentially predict cLBP outcomes for Blacks and Whites, and whether the strength of prediction varies according to SES. This study will be the first to directly and comprehensively apply a socioeconomic framework to the study of racial differences in cLBP outcomes. The findings will also provide novel and important information regarding biopsychosocial predictors of racial and SES differences in clinical pain responses and related disability among those with cLBP. Whether these biopsychosocial predictors may subsequently serve as viable treatment targets for cLBP tailored to meet the specific needs of disadvantaged population subgroups can then be addressed in future research.